Method and apparatus for transmitting and receiving signal by using multiple beams in wireless communication system

ABSTRACT

A method performed by a user equipment (UE) in a wireless communication system includes receiving, from a base station (BS), physical downlink shared channel (PDSCH) configuration information including a list of transmission configuration indicator (TCI) states, receiving, from the BS, a PDSCH media access control element (MAC CE) including information indicating activation of at least one TCI state in the list, identifying whether the PDSCH MAC CE is a MAC CE capable of indicating two or more TCI states for one TCI codepoint, receiving, from the BS, downlink control information (DCI) including information indicating a TCI codepoint, and receiving, from the BS, data via a PDSCH based on the information indicating activation of the at least one TCI state, a result of the identifying, and the information indicating the TCI codepoint.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2019-0036223 filed on Mar. 28, 2019in the Korean Intellectual Property Office, the disclosure of which isincorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to a method and apparatus for transmitting andreceiving a signal by using multiple beams in a wireless communicationsystem.

2. Description of Related Art

An improved 5^(th) generation (5G) communication system or pre-5Gcommunication system is being developed to keep up with explosivelygrowing wireless data traffic demand due to the commercialization of4^(th) generation (4G) communication systems and the increase inmultimedia services. For this reason, the 5G or pre-5G communicationsystem is called a beyond 4G network communication system or a postlong-term evolution (LTE) system.

Implementation of 5G communication systems in an ultra-high frequency(millimeter wave (mmW)) band (such as a 60-GHz band) is underconsideration to increase data transfer rates. To mitigate path loss andincrease transmission distance during radio wave propagation in anultra-high frequency band for 5G communication systems, varioustechnologies such as beamforming, massive multiple-input multiple-output(MIMO), full dimensional MIMO (FD-MIMO), array antennas, analogbeamforming, and large-scale antennas are being studied.

Furthermore, to improve system networks for 5G communication systems,various technologies including evolved small cells, advanced smallcells, cloud radio access network (cloud-RAN), ultra-dense networks,device to device (D2D) communication, wireless backhaul, movingnetworks, cooperative communication, coordinated multi-points (CoMP),and interference cancellation are currently being developed.Furthermore, for 5G systems, advanced coding modulation (ACM) schemessuch as Hybrid FSK and QAM modulation (FQAM) and SWSC (sliding windowsuperposition coding) and advanced access techniques such as filter bankmulticarrier (FBMC), non-orthogonal multiple access (NOMA), sparse codemultiple access (SDMA), etc. are being developed.

Moreover, the Internet has evolved from a human-centered connectionnetwork, in which humans create and consume information, to the internetof things (IoT) network in which dispersed components such as objectsexchange information with one another to process the information. Theinternet of everything (IoE) technology has emerged, in which the IoTtechnology is combined with, for example, technology for processing bigdata through connection with a cloud server. To implement the IoT,technologies such as a sensing technology, a wired/wirelesscommunication and network infrastructure, a service interfacetechnology, and a security technology are required, and thus, researchhas recently been conducted into technologies such as sensor networksfor interconnecting objects, machine to machine (M2M) communication, andmachine type communication (MTC). In an IoT environment, intelligentInternet technology services may be provided to create new values forhuman life by collecting and analyzing data obtained from interconnectedobjects. The IoT can be applied to various fields such as smart homes,smart buildings, smart cities, smart cars or connected cars, a smartgrid, health care, smart home appliances, advanced medical services,etc., through convergence and integration between existing informationtechnology (IT) and various industries.

Thus, various attempts are being made to apply a 5G communication systemto the IoT network. For example, technologies, such as sensor networks,M2M communication, MTC, etc., are implemented using techniques for 5Gcommunication, including beamforming, MIMO, and array antennas. Theapplication of the above-described cloud RAN as a big data processingtechnology is an example of convergence between the 5G and IoTtechnologies.

As various services may be provided due to the aforementioned technicalfeatures and the development of wireless communication systems, inparticular, a method is required which is capable of smoothly supportingcommunications by using a plurality of beams.

SUMMARY

Provided are a method and apparatus capable of effectively providing aservice in a mobile communication system. Also, provided are a methodand apparatus for transmitting and receiving signals by using aplurality of beams.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments of the disclosure.

According to an embodiment of the disclosure, a method performed by auser equipment (UE) in a wireless communication system includesreceiving, from a base station (BS), physical downlink shared channel(PDSCH) configuration information including a list of transmissionconfiguration indicator (TCI) states, receiving, from the BS, a PDSCHmedia access control control element (MAC CE) including informationindicating activation of at least one TCI state in the list, identifyingwhether the PDSCH MAC CE is a MAC CE capable of indicating two or moreTCI states for one TCI codepoint, receiving, from the BS, downlinkcontrol information (DCI) including information indicating a TCIcodepoint, and receiving, from the BS, data via a PDSCH based on theinformation indicating activation of the at least one TCI state, aresult of the identifying, and the information indicating the TCIcodepoint.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1A illustrates a structure of a long term evolution (LTE) systemaccording to an embodiment of the disclosure;

FIG. 1B illustrates a radio protocol architecture for an LTE system,according to an embodiment of the disclosure;

FIG. 1C illustrates a structure of a next-generation mobilecommunication system according to an embodiment of the disclosure;

FIG. 1D illustrates a radio protocol architecture for a next-generationmobile communication system, according to an embodiment of thedisclosure;

FIG. 1E illustrates a structure of a next-generation mobilecommunication system according to an embodiment of the disclosure;

FIG. 1F illustrates a frame structure used in a new radio (NR) system,according to an embodiment of the disclosure;

FIG. 1G illustrates an entire process of indicating, by a base station(BS) in an NR system, a beam for a downlink signal transmitted via aphysical downlink shared channel (PDSCH), according to an embodiment ofthe disclosure;

FIG. 1H illustrates an entire process of indicating, by a BS in an NRsystem, a beam group for downlink signals transmitted in a PDSCH via aplurality of transmission reception points (TRPs), according to anembodiment of the disclosure;

FIG. 1I illustrates a medium access control-control element (MAC CE)structure and a method of activating a candidate downlink beam grouptransmitted from multiple TRPs, according to an embodiment of thedisclosure;

FIG. 1J illustrates a MAC CE structure and a method of activating acandidate downlink beam group transmitted from multiple TRPs, accordingto an embodiment of the disclosure;

FIG. 1K illustrates a MAC CE structure and a method of activating acandidate downlink beam group transmitted from multiple TRPs, accordingto an embodiment of the disclosure;

FIG. 1L illustrates a MAC CE structure and a method of activating acandidate downlink beam group transmitted from multiple TRPs, accordingto an embodiment of the disclosure;

FIG. 1M illustrates a method, performed by a BS, of configuring adownlink beam group via multiple TRPs and communicating with a userequipment (UE), according to an embodiment of the disclosure;

FIG. 1N illustrates a flow chart of a UE operation according to anembodiment of the disclosure;

FIG. 1O illustrates a flow chart of a BS according to an embodiment ofthe disclosure;

FIG. 1P illustrates an internal structure of a UE according to anembodiment of the disclosure; and

FIG. 1Q illustrates a configuration of a BS according to an embodimentof the disclosure.

DETAILED DESCRIPTION

FIGS. 1A through 1Q, discussed below, and the various embodiments usedto describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

Throughout the disclosure, the expression “at least one of a, b or c”indicates only a, only b, only c, both a and b, both a and c, both b andc, all of a, b, and c, or variations thereof.

A terminal may include a user equipment (UE), a mobile station (MS), acellular phone, a smartphone, a computer, or a multimedia system capableof performing a communication function.

In the disclosure, a controller may also be referred to as a processor.

Throughout the specification, a layer (or a layer apparatus) may also bereferred to as an entity.

Hereinafter, operation principles of the disclosure will be described indetail with reference to the accompanying drawings. In the followingdescription of the disclosure, known functions or configurations are notdescribed in detail because they would obscure the essence of thedisclosure with unnecessary detail. Furthermore, the terms used hereinare defined by taking functions described in the disclosure into accountand may be changed according to a user's or operator's intent, orpractices. Therefore, definition of the terms should be made based onthe overall description of the disclosure.

As used in the following description, terms identifying access nodes,terms indicating network entities, terms indicating messages, termsindicating interfaces between network entities, terms indicating varioustypes of identification information, etc. are exemplified forconvenience of description. Accordingly, the disclosure is not limitedto terms to be described later, and other terms representing objectshaving the equivalent technical meaning may be used.

Hereinafter, a base station (BS) is an entity that allocates resourcesto a UE, and may be at least one of a gNode B, an eNode B, a Node B, aBS, a wireless access unit, a BS controller, or a network node. The termterminal may refer to a mobile phone, narrowband Internet of things(NB-IoT) devices, and sensors as well as other wireless communicationdevices. However, the BS and the terminal are not limited to the aboveexamples.

Hereinafter, for convenience of description, the disclosure uses termsand names defined in the 3rd generation partnership project long termevolution (3GPP LTE) and/or 3GPP new radio (3GPP NR) specifications.However, the disclosure is not limited to the terms and names but mayalso be identically applied to systems that comply with other standards.

Because a post LTE communication system, i.e., a 5^(th) generation (5G)communication system, needs to be able to freely reflect variousrequirements from users and service providers, the 5G communicationsystem is required to support services that simultaneously satisfy thevarious requirements. Services being considered for 5G communicationsystems include enhanced mobile broadband (eMBB), massive machine typecommunication (mMTC), ultra-reliable low-latency communication (URLLC),etc.

According to an embodiment of the disclosure, eMBB may aim to providehigher data transfer rates than those supported by the existing LTE,LTE-advanced (LTE-A), or LTE-Pro. For example, in 5G communicationsystems, eMBB may be able to deliver peak data rates of 20 gigabits persecond (Gbps) in downlink and 10 Gbps in uplink from a base station (BS)perspective. Furthermore, the 5G communication systems may be able toprovide better user perceived data rates while simultaneously deliveringthe peak data rates. To meet such requirements, the 5G communicationsystems may require improvement of various transmission/receptiontechnologies including a further improved multi-input multi-output(MIMO) transmission technology. Furthermore, while a current LTE systemtransmits signals by using a maximum transmission bandwidth of 20megahertz (MHz) in the 2 GHz band, a 5G communication system may satisfydata transfer rates required by a 5G technology by using a widerfrequency bandwidth than 20 MHz in the 3 GHz to 6 GHz bands or the bandsabove 6 GHz.

At the same time, mMTC is being considered to support applicationservices such as the Internet of Thing (IoT) in 5G communicationsystems. In order to efficiently provide the IoT, the mMTC may requiresupport of massive connection with terminals in a cell, enhancedterminal coverage, improved battery life, low terminal cost, etc.Because IoT is a system equipped with multiple sensors and variousdevices to provide communication functions, the IoT may be able tosupport a large number of terminals (e.g., one million terminals persquare kilometer (km²) in the cell. Furthermore, because a terminalsupporting the mMTC is highly likely to be located in a shaded area thatcannot be covered by a cell, such as a basement of a building, due tocharacteristics of the service, the mMTC may require wide area coveragecompared to other services provided by a 5G communication system. Theterminal supporting the mMTC may be configured as a low-cost terminaland require a very long battery life-time (e.g., 10 to 15 years) becauseit is difficult to frequently replaced a battery of the terminal.

Lastly, URLLC is a cellular-based wireless communication service usedfor mission-critical applications such as remote control of robots ormachinery, industrial automation, unmanned aerial vehicles (UAVs),remote health care, emergency alert services, etc. Thus, URLLCcommunications may be able to provide very low latency (ultra-lowlatency) and extremely high reliability (ultra-high reliability). Forexample, services supported by URLLC may have to satisfy air interfacelatency of less than 0.5 milliseconds (ms) and simultaneously haverequirements of packet error rate of less than

10⁻⁵. Thus, to support the URLLC services, a 5G system has to provide atransmission time interval (TTI) shorter than for other services and maysimultaneously require a design for allocating wide frequency-bandresources to ensure high reliability of a communication link.

The above-described three services considered in the 5G communicationsystems, i.e., eMBB, URLLC, and mMTC may be multiplexed in one systemfor transmission. Different transmission/reception techniques andtransmission/reception parameters may be used between services tosatisfy different requirements for the respective services. However, themMTC, URLLC, and eMBB are merely examples of different service types,and service types to which the disclosure is applied are not limited tothe above-described examples.

Although embodiments of the disclosure are hereinafter described as anexample of an LTE or LTE-LTE-A system, the embodiments of the disclosuremay be applied to other communication systems having similar technicalbackgrounds and channel configurations. Furthermore, it should beunderstood by those skilled in the art that embodiments of thedisclosure are applicable to other communication systems throughmodifications not departing from the scope of the disclosure.

Hereinafter, embodiments of the disclosure will be described in moredetail with reference to the accompanying drawings.

FIG. 1A illustrates a structure of an LTE system according to anembodiment of the disclosure.

Referring to FIG. 1A, a radio access network for the LTE system consistsof Evolved Node Bs (hereinafter referred to as eNBs, Node Bs, or BSs) 1a-05, 1 a-10, 1 a-15, and 1 a-20, a mobility management entity (MME) 1a-25, and a serving-gateway (S-GW) 1 a-30. A user equipment(hereinafter, referred to as a “UE” or terminal) 1 a-35 connects to anexternal network via the eNBs 1 a-05 through 1 a-20 and the S-GW 1 a-30.

In FIG. 1A, the eNBs 1 a-05 through 1 a-20 correspond to existing nodeBs in a universal mobile telecommunication system (UMTS). The eNBs 1a-05 through 1 a-20 are each connected to the UE 1 a-35 via radiochannels and perform more complicated functions than the existing NodeB. In the LTE system, as all user traffic including real-time serviceslike voice over internet protocol (VoIP) services is served on sharedchannels, an entity may be needed to perform scheduling by collectingstatus information such as buffer states, available transmit powerstates, and channel states for UEs. Each of the eNBs 1 a-05 through 1a-20 may perform the scheduling function. One eNB typically controls aplurality of cells. For example, to achieve a data rate of 100 megabitsper second (Mbps), the LTE system may utilize orthogonal frequencydivision multiplexing (hereinafter abbreviated as OFDM) in a 20 MHzbandwidth as a radio access technology. However, radio accesstechnologies that can be used by the LTE system are not limited to theabove example. Furthermore, the eNBs 1 a-05 through 1 a-20 may applyadaptive modulation & coding (hereinafter abbreviated as AMC) todetermine a modulation scheme and a channel coding rate according tochannel states for UEs. The S-GW 1 a-30 is an entity for providing adata bearer and creates or deletes the data bearer according to controlby the MME 1 a-25. The MME 1 a-25 is responsible for performing variouscontrol functions as well as mobility management for a UE and isconnected to a plurality of BSs.

FIG. 1B illustrates a radio protocol architecture for an LTE system,according to an embodiment of the disclosure.

Referring to FIG. 1B, a radio protocol stack for each of a UE and an eNBin the LTE system may include packet data convergence protocol (PDCP) 1b-05 or 1 b-40, radio link control (RLC) 1 b-10 or 1 b-35, and mediumaccess control (MAC) 1 b-15 or 1 b-30. The PDCP 1 b-05 or 1 b-40 may beresponsible for performing compression/decompression of an IP header.The main functions of the PDCP 1 b-05 or 1 b-40 are summarized asfollows, but are not limited thereto: header compression anddecompression (robust header compression (ROHC) only); transfer of userdata; in-sequence delivery of higher layer packet data units (PDUs) atPDCP re-establishment procedure for RLC acknowledged mode (AM); sequencereordering (for split bearers in dual connectivity (DC) (only supportfor RLC AM): PDCP PDU routing for transmission and PDCP PDU reorderingfor reception); duplicate detection of lower layer service data units(SDUs) at PDCP re-establishment procedure for RLC AM; retransmission ofPDCP SDUs at handover, and for split bearers in DC, retransmission ofPDCP PDUs at PDCP data-recovery procedure for RLC AM; ciphering anddeciphering; timer-based SDU discard in uplink; the RLC 1 b-10 or 1 b-35may reconfigure PDCP PDUs of appropriate size to perform an automaticrepeat request (ARQ) operation. The main functions of the RLC 1 b-10 or1 b-35 may be summarized as follows, but are not limited thereto;transfer of upper layer PDUs; error correction through ARQ (only for AMdata transfer); concatenation, segmentation and reassembly of RLC SDUs(only for UM and AM data transfer); re-segmentation of RLC data PDUs(only for AM data transfer); reordering of RLC data PDUs (only forunacknowledged mode (UM) and AM data transfer); duplicate detection(only for UM and AM data transfer); protocol error detection (only forAM data transfer); RLC SDU discard (only for UM and AM data transfer);and RLC re-establishment.

The MAC b-15 or b-30 is connected with multiple RLC layers configured ina UE and may multiplex RLC PDUs into MAC PDUs and demultiplex RLC PDUsfrom MAC PDUs. The main functions of the MAC b-15 orb-30 may besummarized as follows, but are not limited thereto: mapping betweenlogical channels and transport channels; multiplexing/demultiplexing ofMAC SDUs belonging to one or different logical channels into/fromtransport blocks (TB) delivered to/from the physical layer on transportchannels; scheduling information reporting; error correction throughhybrid ARQ (HARQ); priority handling between logical channels of one UE;priority handling between UEs by means of dynamic scheduling; multimediabroadcast/multicast service (MBMS) service identification; transportformat selection; and padding.

A physical layer (hereinafter, also referred to as a PHY layer) 1 b-20or 1 b-25 may transform higher-layer data into OFDM symbols by means ofchannel coding and modulation and transmit the OFDM symbols via a radiochannel, or transform OFDM symbols received via a radio channel intohigher-layer data by means of demodulation and channel decoding andtransmit the higher-layer data to higher layers. Furthermore, HARQ isused for additional error correction at the physical layer, and at areceiving side, a UE transmits a 1-bit indicator indicating whether theUE has received packets from a transmitting side. The 1-bit indicator iscalled HARQ acknowledgement (ACK)/negative acknowledgement (NACK).Downlink HARQ ACK/NACK for uplink transmission may be transmitted via aphysical HARQ indicator channel (PHICH), while uplink HARQ ACK/NACK fordownlink transmission may be transmitted via a physical uplink controlchannel (PUCCH) or a physical uplink shared channel (PUSCH).

Moreover, the PHY layer may be configured to use one or morefrequencies/carriers, and a technique for simultaneously configuring andusing a plurality of frequencies is referred to as carrier aggregation(CA). According to the CA technique, a primary carrier and one or moresecondary carriers may be employed in communication between a UE and aBS (evolved universal terrestrial radio access network (E-UTRAN) NodeBor eNB), thereby significantly increasing a data rate in proportion tothe number of secondary carriers employed. In LTE, a cell in a BS usinga primary carrier is termed a primary cell (PCell), and the cell using asecondary carrier is termed a secondary cell (SCell).

Although not shown in FIG. 1B, a radio resource control (RRC) layer mayexist on top of the PDCP layer at each of the UE and the BS. The RRClayer may exchange connection and measurement configuration controlmessages for controlling radio resources.

FIG. 1C illustrates a structure of a next-generation mobilecommunication system according to an embodiment of the disclosure.

Referring to FIG. 1A, a radio access network for the next-generationmobile communication system consists of a next-generation BS, i.e., newratio node B (hereinafter, referred to as NR NB, NR gNB, gNB, or NR BS)1 c-10 and a NR core network (NR CN) (or next-generation CN) 1 c-05. AnNR UE (or terminal) 1 c-15 connects to an external network via the NR NB1 c-10 and the NR CN 1 c-05.

In FIG. 1C, the NR NB 1 c-10 corresponds to an eNB in the existing LTEsystem. The NR NB 1 c-10 may be connected to the NR UE 1 c-15 via aradio channel and provide a higher level of service than the existingnode B. In the next-generation mobile communication system, as all usertraffic is served on shared channels, an entity is needed to performscheduling by collecting status information such as buffer states,available transmit power states and channel states for UEs. The NR NB 1c-10 may perform this scheduling function. In general, one NR NBcontrols a plurality of cells. According to an embodiment of thedisclosure, to provide ultra-high-speed data transfer as compared toLTE, the next-generation mobile communication system may have bandwidthswider than the existing maximum bandwidth and utilize OFDM as a radioaccess technology together with an additional beamforming technique.Furthermore, the NR NB 1 c-10 may apply AMC to determine a modulationscheme and a channel coding rate according to a channel state for the NRUE 1 c-15. The NR CN 1 c-05 may perform functions such as mobilitysupport, bearer configuration, quality of service (QoS) configuration,etc. The NR CN 1 c-05 is an entity responsible for performing variouscontrol functions as well as mobility management for a UE and isconnected to a plurality of BSs. Furthermore, the next-generation mobilecommunication system may operate in conjunction with the existing LTEsystem, and the NR CN 1 c-05 is connected with an MME 1 c-25 through anetwork interface. The MME 1 c-25 is connected to an eNB 1 c-30 that isthe existing BS.

FIG. 1D illustrates a radio protocol architecture for a next-generationmobile communication system, according to an embodiment of thedisclosure.

Referring to FIG. 1D, a radio protocol stack for each of a UE and an NRbase station in the next-generation mobile communication system includesNR service data adaptation protocol (NR SDAP) 1 d-01 or 1 d-45, NR PDCP1 d-05 or 1 d-40, NR RLC 1 d-10 or 1 d-35, and NR MAC 1 d-15 or 1 d-30.

According to an embodiment of the disclosure, main functions of the NRSDAP 1 d-01 or 1 d-45 may include some of the following, However, thefunctions of the NR SDAP 1 d-01 or 1 d-45 are not limited to thefollowing: transfer of user plane data; mapping between a QoS flow and adata radio bearer (DRB) for both downlink and uplink; marking a QoS flowID in both downlink and uplink packets; and reflective QoS flow to DRBmapping for uplink SDAP PDUs.

For a SDAP layer, the UE may receive via an RRC message a configurationas to whether to use a header of the SDAP layer or a function of theSDAP layer per PDCP layer, per bearer, or per logical channel. When anSDAP header is configured, a 1-bit non-access stratum (NAS) reflectiveQoS indicator and a 1-bit AS reflective QoS indicator in the SDAP headermay instruct the UE to update or reconfigure information about mappingbetween a QoS flow to a DRB for uplink and downlink. The SDAP header mayinclude QoS flow ID information identifying QoS. Furthermore, accordingto an embodiment of the disclosure, QoS information may be used as apriority for data processing, scheduling information, etc. to support asmooth service.

According to an embodiment of the disclosure, main functions of the NRPDCP 1 d-05 or 1 d-40 may include some of the following functions.However, the functions of the NR PDCP 1 d-05 or 1 d-40 are not limitedto the following example: header compression and decompression: ROHConly; transfer of user data; in-sequence delivery of upper layer PDUs;out-of-sequence delivery of upper layer PDUs; PDCP PDU reordering forreception; duplicate detection of lower layer SDUs; retransmission ofPDCP SDUs; ciphering and deciphering; and timer-based SDU discard inuplink.

According to an embodiment of the disclosure, the reordering function ofan NR PDCP entity may refer to a function of sequentially reorderingPDCP PDUs received from a lower layer based on a PDCP sequence number(SN). The reordering function of the NR PDCP entity may include at leastone of a function of transmitting data to a higher layer in a rearrangedorder, a function of directly transmitting data to a higher layerwithout taking the order into account, a function of rearranging anorder of PDCP PDUs and recording missing PDCP PDUs, a function ofsubmitting a status report indicating missing PDCP PDUs to atransmitting side, or a function of requesting retransmission of missingPDCP PDUs.

According to an embodiment of the disclosure, main functions of the NRRLC 1 d-10 or 1 d-35 may include some of the following. However, thefunctions of the NR RLC 1 d-10 or 1 d-35 are not limited to thefollowing: transfer of upper layer PDUs; in-sequence delivery of upperlayer PDUs; out-of-sequence delivery of upper layer PDUs; errorcorrection through ARQ; concatenation, segmentation and reassembly ofRLC SDUs; re-segmentation of RLC data PDUs; reordering of RLC data PDUs;duplicate detection; protocol error detection; RLC SDU discard; and RLCre-establishment.

According to an embodiment of the disclosure, the in-sequence deliveryfunction of an NR RLC entity may refer to a function of sequentiallytransmitting RLC SDUs received from a lower layer to a higher layer. Thein-sequence delivery function may include at least one of a function of,when one RLC SDU is segmented into multiple RLC SDUs and received,reassembling and transmitting the multiple RLC SDUs, a function ofreordering received RLC PDUs based on an RLC SN or a PDCP SN, a functionof rearranging the order of RLC PDUs and recording missing RLC PDUs, afunction of submitting a status report indicating missing RLC PDUs to atransmitting side, a function of requesting retransmission of missingRLC PDUs, a function of sequentially transmitting, when there is amissing RLC SDU, only RLC SDUs preceding the missing RLC SDU to a higherlayer, a function of sequentially transmitting all of the RLC SDUsreceived before a given timer restarts to a higher layer when the timerexpires before a missing RLC SDU is received, or a function ofsequentially transmitting all of the RLC SDUs received so far to ahigher layer when the given timer expires before a missing RLC SDU isreceived.

Furthermore, according to an embodiment of the disclosure, the NR RLCentity may process RLC PDUs in an order that the RLC PDUs are received(in an order of arrival regardless of the order of serial numbers orSNs) and transmit the RLC PDUs to a PDCP entity regardless of theirorder (e.g., out-of-sequence delivery). Alternatively, the NR RLC entitymay receive segments stored in a buffer or segments to be subsequentlyreceived to reconfigure the segments into one complete RLC PDU and thenprocess the RLC PDU for transmission to the PDCP entity.

According to an embodiment of the disclosure, the NR RLC layer may notinclude a concatenation function. The concatenation function may beperformed at the NR MAC layer or be replaced with the multiplexingfunction of the NR MAC layer.

The out-of-sequence delivery function of the NR RLC entity refers to afunction of directly transmitting RLC SDUs received from a lower layerto a higher layer regardless of their orders. The out-of-sequencedelivery function may include at least one of a function of, when oneRLC SDU is segmented into multiple RLC SDUs and received, reassemblingand transmitting the multiple RLC SDUs or a function of storing RLC SNsor PDCP SNs of received RLC PDUs, arranging the RLC PDUs in a sequentialorder according to the RLC SNs or PDCP SNs, and recording missing RLCPDUs.

According to an embodiment of the disclosure, the NR MAC 1 d-15 or 1d-30 may be connected to multiple NR RLC layers configured in the UE.Main functions of the NR MAC 1 d-15 or 1 d-30 may include some of thefollowing, However, the functions of the NR MAC 1 d-15 or 1 d-30 are notlimited to the following: mapping between logical channels and transportchannels; multiplexing/demultiplexing of the MAC SDUs; schedulinginformation reporting; error correction through HARQ; priority handlingbetween logical channels of one UE; priority handling between UEs bymeans of dynamic scheduling; MBMS service identification; transportformat selection; and padding.

According to an embodiment of the disclosure, an NR PHY layer 1 d-20 or1 d-25 may transform higher-layer data into OFDM symbols by means ofchannel coding and modulation and transmit the OFDM symbols via a radiochannel, or transform OFDM symbols received via a radio channel intohigher-layer data by means of demodulation and channel decoding andtransmit the higher-layer data to higher layers. However, operations ofthe NR PHY layer 1 d-20 or 1 d-25 are not limited thereto.

FIG. 1E illustrates a structure of a next-generation mobilecommunication system according to an embodiment of the disclosure.

Referring to FIG. 1E, a cell served by an NR gNB 1 e-05 operating basedon beams may include a plurality of transmission reception points (TRPs)1 e-10, 1 e-15, 1 e-20, 1 e-25, 1 e-30, 1 e-35 and 1 e-40. The TRPs 1e-10 through 1 e-40 represent a functional block implementing at leastone function that is separated from functions of the existing BS, e.g.,a part of a function of transmitting and receiving physical signals, andeach of the TRPs 1 e-10 through 1 e-40 includes a plurality of antennas.

According to an embodiment of the disclosure, an NR gNB 1 e-05 may berepresented as a central unit (CU), and each TRP may be represented as adistributed unit (DU). Functions of the NR gNB 1 e-05 and the TRP mayeach include some of the PDCP/RLC/MAC/PHY layers shown in 1 e-45 of FIG.1E and functions of the corresponding layers. For example, the TRPs 1e-15 and 1 e-25 only with the PHY layer may perform a function of thecorresponding layer, the TRPs 1 e-10, 1 e-35, and 1 e-40 only with thePHY layer and the MAC layer may perform functions of the correspondinglayers, and the TRPs 1 e-20 and 1 e-30 only with the PHY layer, the MAClayer, and the RLC layer may perform functions of the correspondinglayers.

According to an embodiment of the disclosure, the TRPs 1 e-10 through 1e-40 may use a beamforming technique for generating narrow beams invarious directions via a plurality of transmit and receive antennas inorder to transmit and receive data. A user terminal 1 e-60, i.e., accessand mobility management function (AMF)/session management function (SMF)1 e-50 may connect to the NR gNB 1 e-05 and an external network throughthe TRPs 1 e-10 through 1 e-40. To provide users with services, the NRgNB 1 e-05 may schedule UEs based on collected status information suchas the UEs' buffer states, available transmit power states and channelstates, and in particular, may support a connection between each UE anda CN, in particular, the AMF/SMF 1 e-50.

FIG. 1F illustrates a frame structure used in an NR system, according toan embodiment of the disclosure

Referring to FIG. 4C, the NR system aims at higher data rates comparedto an LTE system and considers the use of high frequencies to ensurewider frequency bandwidths. More particularly, a scenario for the NRsystem may be considered in which directional beams are generated athigh frequencies and data are transmitted at a high rate to a UE byusing the directional beams.

Thus, it is possible to consider a scenario in which an NR gNB or TRP 1f-01 communicates with first through fifth UEs 1 f-71, 1 f-73, 1 f-75, 1f-77, and 1 f-79 in a cell by using different beams for each UE. Forexample, in FIG. 1F, a scenario is assumed in which the first UE 1 f-71communicates with the TRP 1 f-01 using beam #1 1 f-51, the second UE 1f-73 communicates therewith using beam #5 1 f-55, and the third throughfifth UEs 1 f-75 through 1 f-79 communicate therewith using beam #7 1f-57.

To identify beams used by UEs to communicate with the TRP 1 f-01, anoverhead subframe (OSF) 1 f-03 in which a common overhead signal istransmitted is present in the time domain. The OSF 1 f-03 may contain aprimary synchronization signal (PSS) for acquiring the timing of OFDMsymbols, a secondary synchronization signal (SSS) for detecting a cellidentification (ID), etc. Furthermore, the base station may transmit toa UE a physical broadcast channel (PBCH) carrying system information,master information block (MIB), or information necessary for the UE toaccess a system (e.g., a downlink beam bandwidth, a system frame number,etc.). Furthermore, in the OSF 1 f-03, the base station may transmit areference signal by using a different beam for each symbol (or overseveral symbols). The UE may derive a beam index for identifying eachbeam from the reference signal.

It is assumed in FIG. 1F that the NR gNB transmits 12 beams beam #1 1f-51 through beam #12 1 f-62 and that a different beam is swept andtransmitted for each symbol in the OSF 1 f-03. For example, as adifferent beam is transmitted at each symbol (e.g., transmission of beam#1 1 f-51 at a first symbol 1 f-31) in the OSF 1 f-03, the UE maymeasure the OSF 1 f-03 to identify a beam for a signal with a highestsignal strength among beams transmitted in the OSF 1 f-03.

In FIG. 1F, a scenario is assumed that the OSF 1 f-093 is repeated every25 subframes, and in the scenario, the remaining 24 subframes are datasubframes (DSFs) 1 f-05 in which general data is transmitted andreceived. Furthermore, according to scheduling by the base station, thethird through fifth UEs 1 f-75, 1 f-77, and 1 f-79 may communicate usingbeam #7 1 f-11 in common, the first UE 1 f-71 may communicate using beam#1 1 f-13, and the second UE 1 f-73 may communicate using beam #5 1f-55. Although FIG. 1F mainly illustrates transmission beams #1 through#121 f-51 through 1 f-62 of the base station, it is possible to considerreception beams of a UE (e.g., reception beams 1 f-81, 1 f-83, 1 f-85, 1f-87 of the first UE 1 f-71) for receiving transmission beams from thebase station may be additionally considered. For example, referring toFIG. 1F, the first UE 1 f-71 may have the four reception beams 1 f-81, 1f-83, 1 f-85, and 1 f-87 and perform beam sweeping to identify a beamwith the best reception performance from among the four reception beams1 f-81, 1 f-83, 1 f-85, and 1 f-87. Here, when the UE is unable to use aplurality of beams at the same time, the UE may receive as many OSFs asthe number of reception beams, one reception beam for each OSF. Byreceiving a plurality of OSFs respectively corresponding to a pluralityof reception beams, the UE may find an optimal pair of a transmissionbeam of the base station and a reception beam of the UE.

In the disclosure, in conjunction with a transmission configurationindicator (TCI) state used by the base station to indicate a beam usedwhen a UE receives a resource transmitted through a physical downlinkshared channel (PDSCH) in a next-generation mobile communication system,a method of improving a related operation in LTE standard specificationis considered. Although a UE receives an indication of a downlink beamtransmitted via a single TRP according to the related art, the UE mayreceive an indication of downlink beams transmitted from multiple TRPsin a future NR system. However, according to the current standardspecifications, because there is no method by which a base stationindicates downlink beams transmitted via multiple TRPs, an operation forsolving this is required.

FIG. 1G illustrates the entire process of indicating, by a base stationin an NR system, a beam for a downlink signal transmitted via a PDSCH,according to an embodiment of the disclosure.

The NR system is designed to perform data transmission and receptionbetween a UE and a base station by using directional beams. Althoughdata communication using a directional beam may support a high data ratethrough a wide bandwidth and resources related to communication usinghigh frequencies, it may have a limitation that the direction of a beamshould be appropriately determined.

In the NR system, basically, the UE may measure a synchronization signalthrough a synchronization signal/physical broadcast channel (SS/PBCH)block at an initial access phase may perform data transmission andreception in a beam direction in which the synchronization signal isdetected. The base station may configure up to 64 downlink beams for theUE via an RRC message, the downlink beams being used for transmissionthrough a physical downlink control channel (PDCCH), and one beamactually used from among the configured downlink beams may be indicatedvia a MAC control element (MAC CE). Furthermore, the base stationperforms an operation of configuring and indicating a downlink beam usedfor transmission through a PDSCH. In addition, under a predeterminedcondition, a downlink beam for transmission through the PDCCH may beused instead of a downlink beam for transmission through the PDSCH. Forexample, the predetermined condition may be a case in which the timerequired to switch a downlink beam for PDCCH to a downlink beam forPDSCH is shorter than a processing time required to perform theoperation.

Referring to FIG. 1G, a UE 1 g-20 may receive beam configuration forbeam directions 1 g-06 through 1 g-10 of beams in which a channel stateinformation-reference signal (CSI-RS) resource set 1 g-15 is transmittedfrom the base station and the TRP 1 g-05 connected to the UE 1 g-20. Thebeam direction configuration is applicable to a beam via which alltransmission resources delivered through a PDSCH are transmitted, andthe entire process is as follows.

In one example of operation 1 g-25, configure, via RRC configuration, atransmission configuration indicator (TCI) state in a PDSCH-Config foreach bandwidth part (BWP) of a serving cell (up to 128 beams can beconfigured as per LTE standard specification).

In one example of operation 1 g-30: indicate to the UE a candidate beamgroup for activating a TCI state by using a MAC CE, the TCI state beingconfigured by an RRC message and corresponding to a beam via which thePDSCH is transmitted (up to 8 beams, i.e., up to 8 TCI states can beactivated as per LTE standard specification). The purpose of the MAC CEmay be to select candidate beams that can be dynamically indicated viadownlink control information (DCI) among TCI states configured via RRC.Furthermore, the MAC CE may be used to reduce the number of TCI statesto be managed by the UE and the number of bits indicated in the DCI.

In one example of operation 1 g-35, indicate a specific beam among thecandidate beams indicated by the MAC CE via an indicator of DCI(composed of 3 bits as per Rel-15).

FIG. 1H illustrates the entire process of indicating, by a base stationin an NR system, a beam group for downlink signals transmitted in aPDSCH via a plurality of transmission reception points (TRPs), accordingto an embodiment of the disclosure.

As described with reference to FIG. 1G, the NR system is designed toperform data transmission and reception between a UE and a base stationby using directional beams. Although a procedure for configuring andindicating a downlink beam transmitted from a single TRP has beendefined in the LTE standard specification, in a future NR system,multiple TRPs may simultaneously transmit downlink transmissions (forexample, downlink transmissions of associated with a same transportblock (TB)) by using beams configured for one UE. In other words, the UEmay simultaneously receive a configuration for two beams at once, and tosimultaneously receive the indication of the two beams, RRCconfiguration, MAC CE design, and DCI indication operation may need tobe modified. Hereinafter, embodiments of the disclosure provided methodsfor supporting indication of a plurality of beams to a UE.

Referring to FIG. 1H, a UE 1 h-25 may receive beam configuration of beamdirections 1 h-15 through 1 h-20 in which a CSI-RS resource and adownlink resource are transmitted from the base station and multipleTRPs, i.e., first and second TRPs 1 h-05 and 1 h-10, connected to the UE1 h-25. The beam direction configuration may cover all of the first andsecond TRPs 1 h-05 and 1 h-10, and the UE may be able to simultaneouslyreceive a beam direction for one or more TRPs.

In one example of operation 1 h-30, configure, via RRC configuration, aTCI state in a PDSCH-Config for each bandwidth part (BWP) of a servingcell. (In the configuration, TCI states for multiple TRPs (e.g., thefirst TRP 1 h-05 and the second TRP 1 h-10) may be provided as a list inone tci-state field. Alternatively, a separate field (e.g.,tci-state-multipleTRP) for distinguishing the TCI states from anexisting TCI state may be defined. The TCI states associated with themultiple TRPs and the newly introduced tci-state-MultipleTRP field maybe set to a maximum of 128 values with reference to LTE standardspecification, and of course, may be set to 128 or more values.

Alternatively, in the RRC configuration operation, a tci-state-groupfield consisting of a combination of the TCI states transmitted from thefirst TRP 1 h-05 and the second TRP 1 h-10 may be defined, and thecontent of the tci-state-group field may be configured. For example, thetci-state-group field may be configured as {(tci-state #1), (tci-state#1, tci-state #2), (tci-state #2, tci-state #3), . . . , (tci-state#128)}. The maximum number of combinations in the tci-state-group fieldmay be set to 128 or greater with reference to LTE standardspecification).

In one example of operation 1 h-35, indicate to the UE candidate beamgroups (for example, candidate codepoints) for activating TCI states (ortci-state-MultipleTRP or tci-state-group) by using a MAC CE, the TCIstates being configured by an RRC message and corresponding to beamsover which the PDSCH is transmitted through the multiple TRPs. (Thepurpose of the MAC CE may be to select a candidate beam group (forexample, a candidate codepoint) that can be dynamically indicated viaDCI among beams corresponding to TCI states (redefined TCI states,tci-state-multipleTRP, or tci-state-group) configured via RRC.Furthermore, the MAC CE may be used to reduce the number of TCI statesto be managed by the UE and the number of bits indicated in the DCI.

According to the function defined in the previous LTE standardspecification, in the related art, a MAC CE may indicate up to eightcandidate beams, and only configuration of a beam for a single TRP isavailable because only one of the candidate beams can be indicated byDCI. However, because there may be a case in which beams for multipleTRPs are indicated, the modified MAC CE may be able to indicateactivation of the plurality of beams at the same time. The maximumnumber of beam groups transmitted may be extended to eight or sixteen.That is, a candidate activation beam group may consist of a combinationof downlink beams transmitted by using multiple TRPs or beamstransmitted via a single TRP).

In one example of operation 1 h-40, indicate a specific beam group (forexample, a specific codepoint) among candidate beam groups indicated bythe MAC CE via an indicator of DCI. (As per LTE standard specification,indicator bits consist of 3 bits, and in the disclosure, may be composedof 3 or 4 bits. The indicator bits may be determined according to thenumber of beam groups indicated by the MAC CE. The beam group indicatedvia the DCI in operation 1 h-40 means a direction of a downlink beamtransmitted from the multiple TRPs. In other words, the beam groupindicated via the DCI in operation 1 h-40 corresponds to one of thecandidate beam groups for activation indicated in operation 1 h-35.)

In the following embodiments of the disclosure, methods for supportingthe system described with reference to FIG. 1H, and in particular, thestructure of the MAC CE and RRC configuration will be described. Mattersto be considered for downlink beam indication in the multi-TRP system ofFIG. 1H are as follows. Hereinafter, a “code point” (or, a codepoint)may be information (or value) indicated by the MAC CE in operation 1h-35. For example, the code point may include single beam information orbeam group information indicated by the MAC CE.

In one example, one or two TRPs (or TCI states) may be included in onecode point (a beam group indicated by the MAC CE). In other words, adownlink transmission may be a transmission from a single TRP or may betransmissions from multiple TRPs.

In one example, the maximum number of code points activated in the MACCE may be 8 or 16.

In one example, in association with a maximum code point, the number ofDCI activation indication bits may be determined to be 3 or 4.

In one example, the newly defined MAC CE may be able to distinguish codepoints. In other words, directions of beams transmitted simultaneouslyfrom the first TRP 1 h-05 and the second TRP 1 h-10 (for examples,directions of beams associated with a same transport block (TB)) may beconfigured in one code point as a beam combination.

In one example, it is possible to solve beam indication in the multi-TRPsystem by changing a MAC CE alone or in association with an RRC.

In one example of a solution based on RRC change: a new field (e.g.,TCI-StateMultipleTRP) is defined and 128 code points in the new fieldare arranged as a list. The code point consists of up to two TCI states;and the new MAC CE uses a “V” field instead of the existing “R” field,and when the “V” field is set to 1, the MAC CE applies the newly definedTCI-StateMultipleTRP instead of the TCI-State configured via theexisting RRC message.

In one example of a solution based on MAC CE change: a TCI-Stateconfigured in the existing RRC is maintained. Alternatively, thestructure of the TCI-State configuration may be maintained, but actuallyconfigured TCI state may be indicated considering multiple TRPs; and anew MAC CE is designed to simultaneously indicate a plurality of beamgroups.

A method provided in the following embodiment of the disclosure is forapplying a MAC CE defined in LTE standard specification as TCI statesactivation/deactivation for UE-specific PDSCH MAC CE to multiple TRPs,which will be understood with reference to the existing MAC CEstructure.

FIG. 1I illustrates a MAC CE structure and a method of activating acandidate downlink beam group transmitted from multiple TRPs, accordingto an embodiment of the disclosure.

According to an embodiment of the disclosure, the MAC CE structureprovided with reference to FIG. 1I may correspond to reused “TCI statesactivation/deactivation for UE-specific PDSCH MAC CE” currently definedin the LTE standard specification. That is, a logical channel ID (LCD)for the MAC CE structure shown in FIG. 1I may have the same value as thepreviously defined LCD.

When a field 1 i-05 previously set to an “R” field is set to a “V” fieldand the “V” field is set to 1 in a MAC CE structure, the MAC CEstructure is defined to be a MAC CE structure supporting multiple TRPsas specified in LTE standard specification. Furthermore, as in aprevious version of MAC CE, a serving cell ID field 1 i-10 and a BWP IDfield 1 i-15 are included in the MAC CE to respectively indicate aserving cell to which a beam belongs and a BWP.

A difference from the previous version of MAC CE is that the previousversion of MAC CE indicates up to eight candidate downlink activationbeams (“T” fields) while in the MAC CE structure shown in FIG. 1I, beamsfor TRP 1 and TRP 2 successively form the same combination.

For example, in the existing MAC CE structure, eight “T” fields are setto 1. On the other hand, in the new MAC CE structure, sixteen “T” fields1 i-20 corresponding to double the eight “T” fields may be all set to 1,and first and second activated fields may form a combination for fieldsactivated with 1 to indicate a first beam combination for TRP1 and TRP2. Similarly, third and fourth activated fields may form a combinationto indicate a second beam combination for TRP 1 and TRP 2. In the samemanner, fifteenth and sixteenth activated fields may form a combinationto indicate an eighth beam combination for TRP 1 and TRP 2.

The above-described MAC CE structure may be used under the assumptionthat each combination for TRP 1 and TRP 2 may always consist of twoactivated fields. The MAC CE structure is also characterized in that “T”fields having a number corresponding to a multiple of 2 are alwaysactivated. In addition, in the above-described MAC CE structure, as manycode points as the number of the set “T” fields divided by two may beset.

FIG. 1J illustrates a MAC CE structure and a method of activating acandidate downlink beam group transmitted from multiple TRPs, accordingto an embodiment of the disclosure.

A MAC CE structure provided with reference to FIG. 1J may be similar tothat shown in FIG. 1I in the MAC CE structure corresponding to the “TCIstates activation/deactivation for UE-specific PDSCH MAC CE” currentlydefined in the LTE standard specification is reused. (i.e., an LCD forthe MAC CE structure shown in FIG. 1J has the same value as thepreviously defined LCD). However, the MAC CE structure provided withreference to FIG. 1J differs from the existing MAC CE structure in size,and the MAC CE structure provided with reference to FIG. 1J differs fromthe MAC CE structure provided with reference to FIG. 1I in that the MACCE structure provided with reference to FIG. 1J is further extended.

As in FIG. 1I, a new “V” field may be introduced in 1 j-05 todistinguish a MAC CE format in the previous LTE standard specificationfrom a MAC CE format in the LTE standard specification. When the “V”field is set to 1, the MAC CE structure is defined to be a MAC CEstructure supporting multiple TRPs as specified in LTE standardspecification. Furthermore, as in a previous version of MAC CE, aserving cell ID field 1 j-10 and a BWP ID field 1 j-15 are included inthe MAC CE structure to respectively indicate a serving cell to which abeam belongs and a BWP.

In addition, “T” fields 1 j-20 represent beams activated in TRP 1 as inthe existing “T” fields. When the number of activated “T” fields is setto N, N sets of “C” fields 1 j-25 and N sets of “TCI state ID” fields 1j-30 may be present in the MAC CE structure. Furthermore, a combinationof the “C” field 1 j-25 and the “TCI state ID” field 1 j-30 issequentially mapped to the activated “T” field. For example, a firstactivated “T” field, a first “C” field, and a first “TCI state ID” fieldare mapped as one combination.

The “TCI state ID” field 1 j-30 is used to indicate a beam applied toTRP 2 and may have a length of 7 bits. In other words, because themaximum number of TCI states configured via RRC is 128, the “TCI stateID” field 1 j-30 may be set to 7 bits to indicate a candidate beam thatmay be configured in TRP 2. When the number of TCI states that can beconfigured via RRC increases, the size of the “TCI state ID” field 1j-30 may also increase correspondingly.

The “C” field 1 j-25 is an indicator indicating whether the “TCI stateID” field 1 j-30 that may be present later actually exists in the MAC CEstructure. When the “C” field 1 j-25 is set to 1, “TCI state ID” fieldto be present later indicates a TCI state for TRP 2. When the “C” field1 j-25 is set to 0, the “TCI state ID” field to be present later isfilled with a meaningless value. In other words, the UE may ignore the“TCI state ID” field 1 j-30, or the base station may set the “TCI stateID” field 1 j-30 to the same ID as that of an activated TCI stateindicating a beam from the TRP 1.

FIG. 1K illustrates a MAC CE structure and a method of activating acandidate downlink beam group transmitted from multiple TRPs, accordingto an embodiment of the disclosure.

In an embodiment of the disclosure provided with reference to FIG. 1K, anew MAC CE for indicating a downlink beam group via multiple TRPs isintroduced. For example, a new MAC CE structure different from theexisting TCI state activation/deactivation MAC CE for the PDSCH may beintroduced, and a new LCD may be used. According to the embodimentprovided with reference to FIG. 1K, a MAC CE may be designed to have acompletely new structure, so that the MAC CE may be designed with anoptimal structure indicating a downlink beam group via multiple TRPs.

Referring to FIG. 1K, the new MAC CE structure is similar to theexisting MAC CE structure in that an “R” field 1 k-05, a serving cell IDfield 1 k-10, and a BWP ID field 1 k-15 indicate a serving cell to whicha beam group indicated by the MAC CE belongs and a BWP. In the followingdescription, a MAC CE 1 k-01 according to a first option isdistinguished from a MAC CE 1 k-02 according to a second optiondepending on the presence/absence of a subfield, in particular, a “TCIcode ID” field.

First, the MAC CE 1 k-01 according to the first option will bedescribed. A subsequent field group excluding the “R” field 1 k-05, theserving cell ID field 1 k-10, and the BWP ID field 1 k-15 may be able toindicate TCI state IDs (via TCI state ID fields 1 k-30, 1 k-35, 1 k-50,and 1 k-55) identifying TCI states used for TRP1 and TRP2 and mayexplicitly allocate TCI code ID fields 1 k-20 and 1 k-40 to which TCIcode points are assigned. Furthermore, “C” fields 1 k-25 and 1 k-45 areconfigured as indicators indicating the presence of TCI state IDs (i.e.,the TCI state ID fields 1 k-35 and 1 k-55) corresponding to downlinkbeams indicated via TRP 2.

For example, the MAC CE 1 k-01 according to the first option may have astructure as follows: R field (1 bit)+serving cell ID (5 bits)+BWP ID (2bits)+a set of {TCI code ID (3˜1 eits)+indication for TRP2 TCI state (1bit)+TCI state for TRP1 (7 bits)+reserved bit (1 bit)+TCI state for TRP2(7 bits)}.

Unlike in the MAC CE 1 k-01 according to the first option, a “TCI codeID” field may be omitted in the MAC CE 1 k-02 according to the secondoption. Even when there is no “TCI code ID” field, TCI states may besequentially indicated by the MAC CE, and the UE may infer the totalnumber of TCI codes indicated through a size of the entire MAC CE.

For example, the MAC CE 1 k-02 according to the second option may have astructure as follows. R field (1 bit)+serving cell ID (5 bits)+BWP ID (2bits)+a set of {indication for TRP2 TCI state (1 bit)+TCI state for TRP1(7 bits)+reserved bit (1 bit)+TCI state for TRP2 (7 bits)}.

In the MAC CE 1 k-02, each of TCI state IDx (x is one of 1,2, . . . , N)may correspond to one codepoint. One codepoint may include a TCI stateID for TRP1 and may additionally include a TCI state ID for TRP2.

According to the embodiment provided with reference to FIG. 1K, a newMAC CE is introduced without reusing the existing MAC CE. In thisembodiment, a new LCID may be required. When the UE receives a MAC PDU,the UE checks the LCID through the sub-header information of thereceived MAC PDU, and identifies that the received MAC CE is a new MACCE which may be used to activate/deactivate two or more TCI statescorresponding to multiple TRPs by only one PDCCH.

According to the embodiment provided with reference to FIG. 1K, byintroducing the “C” field in the MAC CE, it is possible to indicatewhether an indication for TRP2 exists for each TCI code points activatedby the MAC CE. Through the introduction of the “C” field, the MAC CEsize can be flexibly adjusted, and in the case where the TCI stateindication for TRP2 is not required, the overhead of the corresponding 1byte can be reduced, thereby reducing the signaling load.

FIG. 1L illustrates a MAC CE structure and a method of activating acandidate downlink beam group transmitted from multiple TRPs, accordingto an embodiment of the disclosure.

According to an embodiment of the disclosure provided with reference toFIG. 1L, a newly introduced MAC CE includes only a portion that cannotbe indicated by the above-described existing MAC CE while reusing a MACCE corresponding to “TCI states activation/deactivation for UE-specificPDSCH MAC CE” currently defined in the LTE standard specification. Inother words, according to the embodiment provided with reference to FIG.1L, to indicate downlink beams for TRP 1 and TRP 2, configurationinformation may be transmitted by transmitting the newly defined MAC CEtogether with the existing MAC CE.

Referring to FIG. 1L, the existing MAC CE structure 1 l-03 includes areserved bit 1 l-05, a serving cell ID field 1 l-10, a BWP ID field 1l-15, and TCI state bitmap “T” fields 1 l-20 indicating activation. Theexisting MAC CE structure 1 l-03 may indicate a candidate downlinkactivation beam for TRP 1. A new MAC CE structure for indicating acandidate downlink activation beam for TRP 2 may be defined according totwo options.

First, a MAC CE 1 l-01 according to a first option will be described.the MAC CE 1 l-01 according to the first option may be able to indicateTCI state IDs (via TCI state ID fields 1 l-50 and 1 l-65) identifyingTCI states used for TRP2 corresponding to TRP1 and may explicitlyallocate TCI code ID fields 1 l-40 and 1 l-55 for mapping the same TCIcode points as for TRP1. Furthermore, “C” fields 1 l-45 and 1 l-60 areconfigured as indicators indicating the presence of TCI state IDs(indicated via the TCI state ID fields 1 l-50 and 1 l-65) correspondingto downlink beams indicated via TRP 2. When the “C” fields 1 l-45 and 1l-60 are set to 1, the TCI state ID fields 1 l-50 and 1 l-65 indicatingTCI state IDs corresponding to downlink beams indicated via TRP 2 arepresent. When the “C” fields 1 l-45 and 1 l-60 are set to 0, there is nobeam indicated through TRP 2. When the “C” fields 1 l-45 and 1 l-60 areset to 0, the UE may ignore the TCI state ID fields 1 l-50 and 1 l-65,or the base station may set the TCI state ID fields 1 l-50 and 1 l-65 tothe same IDs as that of activated TCI states indicating beams from theTRP 1 respectively.

A MAC CE 1 l-02 according to the second option differs from the MACstructure 1 l-01 according to the first option in that the MAC CE 1 l-02does not include TCI code ID fields 1 l-40 and 1 l-55. The MAC CEs 1l-01 and 1 l-02 according to the first and second options mayrespectively have the following structures: MAC CE 1 l-01 according tofirst option: R field (1 bit)+serving cell ID (5 bits)+BWP ID (2 bits)+aset of {TCI code ID (3˜1 eits)+indication for TRP2 TCI state (1bit)+reserved bit (1 bit)+TCI state for TRP2 (7 bits)}; and MAC CE 1l-02 according to second option: R field (1 bit)+serving cell ID (5bits)+BWP ID (2 bits)+a set of {indication for TRP2 TCI state (1bit)+TCI state for TRP2 (7 bits)}.

According to an embodiment of the disclosure, in the newly defined MACCE, a serving cell ID field and a BWP ID field may be omitted in aspecial situation. For example, the special situation may be a situationin which the existing MAC CE and the new MAC CE are transmitted in thesame MAC PDU. Alternatively, when the serving cell ID field and the BWPID field are omitted in the newly defined MAC CE, the MAC CE may bedefined as having the same serving cell ID and BWP ID as in the previousMAC CE.

FIG. 1M illustrates a method, performed by a BS, configuring a downlinkbeam group via multiple TRPs and communicating with a UE, according toan embodiment of the disclosure.

Referring to FIG. 1M, a UE 1 m-01 in an idle mode RRC_IDLE searches fora suitable cell and camps on a gNB 1 m-03 (operation 1 m-05). Upongeneration of data to be transmitted or the like, the UE 1 m-01 performsa connection to the gNB (operation 1 m-10). While in an idle mode, theUE is not connected to a network for power saving or the like, so the UEcannot transmit data. The UE needs to switch the idle mode to aconnected mode RRC_CONNECTED for transmission of data. When the UE campson a cell, the UE stays in the cell and receives a paging message tomonitor whether data is incoming via a downlink. When the UE 1 m-01successfully establishes the connection to the gNB 1 m-03, the UEtransits to the connected mode RRC_CONNECTED. The UE 1 m-01 in theconnected mode may transmit and receive data to and from the gNB 1 m-03(operation 1 m-15).

When in the RRC-connected state, the gNB 1 m-03 transmits configurationinformation related to a TCI state to the UE 1 m-01 through an RRCmessage (operation 1 m-20). An operation of transmitting the RRC messagealso includes an operation of configuring, through a TCI state, adownlink beam used for transmission via a PDCCH and a PDSCH. Downlinkbeam configuration is performed per serving cell and per BWP and isincluded in PDCCH-Config and PDSCH-Config, respectively. For example, inLTE standard specification, the gNB 1 m-03 configures, via RRC messages,up to 64 downlink beams used for transmission through the PDCCH to theUE 1 m-01, and one actually used beam from among downlink beams areindicated via a MAC CE. Furthermore, the gNB 1 m-03 performs anoperation of configuring and indicating a downlink beam used fortransmission through the PDSCH. Moreover, under a predeterminedcondition, a downlink beam used for transmission through a PDCCH may beused instead of a downlink beam used for transmission through a PDSCH.For example, the predetermined condition may be a case where aprocessing time takes to switch a downlink beam for PDCCH to a downlinkbeam for PDSCH is shorter than a required processing time for performingthe switching operation.

According to an embodiment of the disclosure, even when a downlink beamis indicated via multiple TRPs, a TCI state transmitted through a PDSCHfrom multiple TRPs for each serving cell and for each BWP may beconfigured in a manner similar to that described in operation 1 m-20. Asdescribed above, the TCI state may be configured by reusing a TCI statefield included in the existing RRC control information, or byintroducing a new separate field. Furthermore, the maximum number ofconfigurable TCI states may be 128 or greater (e.g., 256). When the TCIstate field is set, an actual TCI state value set in the TCI state fieldmay indicate beams for TRP1 and TRP2. Before transmitting the RRCmessage for configuring the TCI state to the UE 1 m-01, the gNB 1 m-03may request UE capabilities and receive a UE capability report from theUE 1 m-01 and analyze the gNB's TRP capabilities, UE capabilities forprocessing downlink beams via multiple TRPs, etc., to determine whichTRP beam information is to be included in the TCI state based on ananalysis result.

The gNB 1 m-03 may activate a plurality of beams or beam groups that canbe activated according to a position and a state of the UE 1 m-01 amongTCI state values set via RRC configuration information (operation 1m-25). As described in the foregoing operations, the gNB 1 m-03 maydetermine which version of MAC CE is to be activated by the UE 1 m-01.The gNB 1 m-03 may indicate activation of candidate beams for a singleTRP and candidate beam groups for multiple TRPs.

The gNB 1 m-03 indicates, via an indicator of DCI, one code point amonga plurality of downlink beam groups (code points) for which activationis indicated in operation 1 m-25 (operation 1 m-30).

The UE 1 m-01 performs downlink data reception using a beam configuredfor communication with the gNB 1 m-03 (operation 1 m-35).

The gNB 1 m-03 may retransmit the MAC CE for the purpose of updating thepreviously delivered MAC CE and may update beam groups that arerespectively activated and deactivated (operation 1 m-40).

The gNB 1 m-03 may indicate one of the beam groups activated inoperation 1 m-40 and instruct the UE 1 m-01 to use one of the beamgroups as a downlink beam group (operation 1 m-45).

FIG. 1N illustrates a flow chart of a UE according to an embodiment ofthe disclosure.

Referring to FIG. 1N, the UE performs an RRC connection procedure with agNB and transits to an RRC connected state (operation 1 n-05). The UEreceives configuration information for a TCI state (“TCI stateconfiguration information”) from the gNB via a RRCReconfigurationmessage (operation 1 n-10). The TCI state configuration information mayinclude beam configuration information received via a PDCCH and beamconfiguration information received via a PDSCH. Furthermore, beforereceiving the TCI state configuration information, the UE may report UEcapabilities to the gNB.

The TCI state configuration information refers to downlink beamconfiguration information of the UE. The TCI state configurationinformation may include beam group configuration information formultiple TRPs. For example, when the UE reports information indicatingthat the UE supports beam group configuration for multiple TRPs whilereporting the UE capabilities, the TCI state configuration informationmay include beam group configuration information for the multiple TRPs.

The UE may receive a MAC CE indicating PDSCH beam group activation formultiple TRPs from the gNB (operation 1 n-15). The MAC CE may have astructure described with reference to FIG. 1I, 1J, 1K, or 1L.

The UE may identify the type of the received MAC CE to determine whetherthe MAC CE is a beam activation indication for a single TRP or a beamactivation indication for multiple TRPs and then perform differentoperations according to a determination result (operation 1 n-20). Forexample, the UE may determine the type of MAC CE by checking an LCDvalue or a specific indicator (e. g., a “V” field) in the MAC CE.

When the received MAC CE is a beam activation MAC CE for a single TRP(e.g., MAC CE for the existing LTE standard specification), the UE maystore an activated candidate beam (TCI state) applied to a single TRP(operation 1 n-25). The UE may receive DCI including an indication of anactually used TCI state value from the gNB (operation 1 n-30). The UEmay perform downlink data reception and CSI reporting by using theindicated downlink beam (operation 1 n-35).

When the MAC CE received by the UE in operation 1 n-20 is a beamactivation MAC CE for multiple TRPs (e. g., a newly defined MAC CE), theUE may store an activated candidate beam group (a TCI code point)applied to the multiple TRPs (operation 1 n-40). The UE may receive DCIincluding an indication of an actually used TCI code point from the gNB(operation 1 n-45). The UE may perform downlink data reception and CSIreporting by using an indicated downlink beam group (beam configurationsfor TRP 1 and TRP 2) (operation 1 n-50).

FIG. 1O illustrates a flow chart of a gNB according to an embodiment ofthe disclosure.

Referring to FIG. 1O, the gNB may establish an RRC connection with a UE(operation 1 o-05).

The gNB may request UE capabilities from the UE and receive UEcapability information from the UE (operation 1 o-10). The gNB maydetermine whether the UE is able to apply a downlink beam groupconfiguration for multiple TRPs by analyzing the received UE capabilityinformation and check whether the UE is able to configure a downlinkbeam group for multiple TRPs to the UE (i.e., by checking whether theconfiguration for the multiple TRPs is possible and whether requirementsnecessary for the configuration are satisfied).

Based on a result of checking whether configuring the UE withtransmissions using the multiple TRPs is possible, the gNB may providethe UE with TCI state configuration information via an RRC message, theTCI state configuration information including a beam configuration forthe multiple TRPs according to UE capabilities and TRP support. When theUE has no capability for the configuration for the multiple TRPs or whenthe gNB determines that the configuration for the multiple TRPs is notnecessary, the gNB may provide the UE with TCI state configurationinformation including a beam configuration for a single TRP instead ofthe TCI state configuration information including a beam configurationfor the multiple TRPs.

The gNB may transmit to the UE a MAC CE indicating PDSCH beam groupactivation for multiple TRPs (operation 1 o-20). The MAC CE may have astructure described with reference to FIG. 1I, 1J, 1K, or 1L.Furthermore, a method of determining a beam group indicated by the MACCE may be determined based on beam reporting by the UE and informationsuch as beam information previously configured to the UE. In addition,the gNB may always configure a beam combination for TRP 1 and TRP 2 whenindicating a beam group via the MAC CE or may activate a beam from asingle TRP.

The gNB may indicate, via DCI, one beam or beam group to be actuallyused for downlink data transmission among candidate activation beams orbeam groups indicated by the MAC CE (operation 1 o-25). For example, thegNB may indicate the beam or beam group to be used via a beam indicatorincluded in the DCI.

The gNB transmits downlink data to the UE through a configured beamdirection (operation 1 o-30).

FIG. 1P illustrates an internal structure of a UE according to anembodiment of the disclosure.

Referring to FIG. 1P, the UE may include a radio frequency (RF)processor 1 p-10, a baseband processor 1 p-20, a storage 1 p-30, and acontroller 1 p-40. The controller 1 p-40 includes a multi-connectivityprocessor 1 p-42. The internal structure of the UE is not limited to theabove example, and the UE may include fewer or more components thatthose shown in FIG. 1P.

The RF processor 1 p-10 performs a function for transmitting andreceiving a signal via a radio channel, such as signal conversionbetween bands and amplification. For example, the RF processor 1 p-10may upconvert a baseband signal from the baseband processor 1 p-20 intoan RF signal and transmit the RF signal via an antenna, and downconvertan RF signal received via the antenna into a baseband signal. Forexample, the RF processor 1 p-10 may include a transmit filter, areceive filter, an amplifier, a mixer, an oscillator, a digital toanalog convertor (DAC), an analog to digital convertor (ADC), etc.Although only one antenna is shown in FIG. 1P, the UE may have aplurality of antennas.

The RF processor 1 p-10 may also include a plurality of RF chains.Furthermore, the RF processor 1 p-10 may perform beamforming. Forbeamforming, the RF processor 1 p-10 may adjust a phase and a magnitudeof each of the signals transmitted and received through a plurality ofantennas or antenna elements. Furthermore, the RF processor 1 p-10 mayperform a MIMO operation during which multiple layers may be received.The RF processor 1 p-10 may perform reception beam sweeping byappropriately configuring a plurality of antennas or antenna elementsaccording to control by the controller 1 p-40 or adjust a direction andwidth of a reception beam so that the reception beam is aligned with atransmission beam.

The baseband processor 1 p-20 may perform a function for conversionbetween a baseband signal and a bit string according to the physicallayer standard of the system. For example, when transmitting data, thebaseband processor 1 p-20 may generate complex symbols by encoding andmodulating a transmission bit string. Furthermore, when receiving data,the baseband processor 1 p-20 may reconstruct a reception bit string bydemodulating and decoding a baseband signal from the RF processor 1p-10. For example, according to an OFDM scheme, when transmitting data,the baseband processor 1 p-20 may generate complex symbols by encodingand modulating a transmission bit string, map the complex symbols tosubcarriers, and generate OFDM symbols through inverse fast Fouriertransform (IFFT) operations and cyclic prefix (CP) insertionFurthermore, when receiving data, the baseband processor 1 p-20 maydivide the baseband signal from the RF processor 1 p-10 into OFDMsymbols, recover signals mapped to subcarriers through FFT operations,and reconstruct a reception bit string through demodulation anddecoding.

As described above, the baseband processor 1 p-20 and the RF processor 1p-10 transmit and receive a signal. Thus, the baseband processor 1 p-20and the RF processor 1 p-10 may be referred to as a transmitter,receiver, transceiver, or communicator. Furthermore, at least one of thebaseband processor 1 p-20 or the RF processor 1 p-10 may include aplurality of communication modules to support different radio accesstechnologies. In addition, at least one of the baseband processor 1 p-20or the RF processor 1 p-10 may include different communication modulesto process signals in different frequency bands. For example, thedifferent radio access technologies may include a wireless local areanetwork (WLAN) technology (e.g., institute of electrical and electronicsengineers (IEEE) 802.11), a cellular network technology (e.g., LTE),etc. The different frequency bands may include super-high frequency(SHF) bands (e.g., 2. NRHz, NRhz) and millimeter (mm)-wave bands (e.g.,60 GHz). The UE may transmit and receive a signal to and from a basestation via the baseband processor 1 p-20 and the RF processor 1 p-10,and the signal may include control information and data.

The storage 1 p-30 stores basic programs, application programs, and datasuch as configuration information for operations of the UE. The storage1 p-30 provides stored data at the request of the controller 1 p-40. Thestorage 1 p-30 may be composed of storage media, such as read-onlymemory (ROM), random access memory (RAM), hard discs, compact disc(CD)-ROM, and digital versatile discs (DVDs), or a combination thereof.Furthermore, the storage 1 p-30 may include a plurality of memories.

The controller 1 p-40 may control all operations of the UE. For example,the controller 1 p-40 may transmit and receive a signal via the basebandprocessor 1 p-20 and the RF processor 1 p-10. The controller 1 p-40 alsowrites and reads data to and from the storage 1 p-30. To do so, thecontroller 1 p-40 may include at least one processor. For example, thecontroller 1 p-40 may include a communication processor (CP) to controlcommunication and an application processor (AP) to control higher layerssuch as application programs. Furthermore, the controller 1 p-40 maycontrol the UE to perform a method of receiving a downlink signal byusing the above-described multiple beams. Furthermore, at least onecomponent in the UE may be implemented as a single chip.

FIG. 1Q illustrates a configuration of a base station according to anembodiment of the disclosure.

Referring to FIG. 1Q, the base station may include an RF processor 1q-10, a baseband processor 1 q-20, a backhaul communicator 1 q-30, astorage 1 q-40, and a controller 1 q-50. The controller 1 q-50 mayinclude a multi-connectivity processor 1 q-52. The internal structure ofthe base station is not limited to the above example, and the basestation may include fewer or more components that those shown in FIG.1Q.

The RF processor 1 q-10 performs a function for transmitting andreceiving a signal via a radio channel, such as signal conversionbetween bands and amplification. For example, the RF processor 1 q-10may upconvert a baseband signal from the baseband processor 1 q-20 intoan RF signal and transmit the RF signal via an antenna, and downconvertan RF signal received via the antenna into a baseband signal. Forexample, the RF processor 1 q-10 may include a transmit filter, areceive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC,etc. Although only one antenna is shown in FIG. 1Q, the base station mayhave a plurality of antennas. The RF processor 1 q-10 may include aplurality of RF chains. Furthermore, the RF processor 1 q-10 may performbeamforming. For beamforming, the RF processor 1 q-10 may adjust a phaseand magnitude of each of the signals transmitted and received through aplurality of antennas or antenna elements. Furthermore, the RF processor1 q-10 may perform a MIMO operation by transmitting one or more layers.

The baseband processor 1 q-20 may perform a function for conversionbetween a baseband signal and a bit string according to the physicallayer standard of a radio access technology. For example, whentransmitting data, the baseband processor 1 q-20 may generate complexsymbols by encoding and modulating a transmission bit string. Whenreceiving data, the baseband processor 1 q-20 may reconstruct areception bit string by demodulating and decoding a baseband signal fromthe RF processor 1 q-10. For example, according to an OFDM scheme, whentransmitting data, the baseband processor 1 q-20 may generate complexsymbols by encoding and modulating a transmission bit string, map thecomplex symbols to subcarriers, and generate OFDM symbols through IFFToperations and CP insertion. Furthermore, when receiving data, thebaseband processor 1 q-20 may divide the baseband signal from the RFprocessor 1 q-10 into OFDM symbols, recover signals mapped tosubcarriers through FFT operations, and reconstruct a reception bitstring through demodulation and decoding. As described above, thebaseband processor 1 q-20 and the RF processor 1 q-10 transmit andreceive signals. Thus, the baseband processor 1 q-20 and the RFprocessor 1 q-10 may be referred to as a transmitter, receiver,transceiver, communicator, or wireless communicator. The base stationmay transmit and receive a signal to and from the UE via the basebandprocessor 1 q-20 and the RF processor 1 q-10, and the signal may includecontrol information and data.

The backhaul communicator 1 q-30 may provide an interface to communicatewith other nodes in the network. For example, the backhaul communicator1 q-30 may convert a bit string to be transmitted from a primary BS toanother node, such as a secondary BS and a CN, into a physical signal,and may convert a physical signal received from the other node into abit string.

The storage 1 q-40 may store basic programs, application programs, anddata such as configuration information for operations of the basestation. In particular, the storage 1 q-40 may store information aboutbearers allocated to a connected UE, measurement results reported by theconnected UE, etc. Furthermore, the storage 1 q-40 may store informationthat is a criterion for determining whether to provide or terminatemultiple connectivity to or from the UE. The storage 1 q-40 providesstored data at the request of the controller 1 q-50. The storage 1 p-30may be composed of storage media, such as ROM, RAM, hard discs, CD-ROM,and DVDs, or a combination thereof. Furthermore, the storage 1 q-40 mayinclude a plurality of memories.

The controller 1 q-50 controls all operations of the base station. Forexample, the controller 1 q-50 transmits and receives a signal throughthe baseband processor 1 q-20 and the RF processor 1 q-10 or through thebackhaul communicator 1 q-30. Furthermore, the controller 1 q-50 writesand reads data to and from the storage 1 q-40. To do so, the controller1 q-50 may include at least one processor. Furthermore, the controller 1q-50 may control the base station such that the UE may perform a methodof receiving a downlink signal by using the above-described multiplebeams. In addition, at least one component in the base station may beimplemented as a single chip.

The methods according to the embodiments of the disclosure described inthe appended claims or specification thereof may be implemented inhardware, software, or a combination of hardware and software.

When the methods are implemented in software, a computer-readablestorage medium storing at least one program (software module) may beprovided. The at least one program stored in the computer-readablestorage medium is configured for execution by at least one processorwithin an electronic device. The at least one program includesinstructions that cause the electronic device to execute the methodsaccording to the embodiments of the disclosure described in the claimsor specification thereof.

The program (software module or software) may be stored in RAM,non-volatile memory including a flash memory, ROM, electrically erasableprogrammable ROM (EEPROM), a magnetic disc storage device, CD-ROM, DVDsor other types of optical storage devices, and a magnetic cassette.Alternatively, the program may be stored in a memory that is configuredas a combination of some or all of the memories. A plurality of suchmemories may be included.

Furthermore, the program may be stored in an attachable storage devicethat may be accessed through communication networks such as theInternet, Intranet, a local area network (LAN), a wide LAN (WLAN), and astorage area network (SAN) or a communication network configured in acombination thereof. The storage device may access a device performingmethods according to the embodiments of the disclosure through anexternal port. Further, a separate storage device on the communicationnetwork may also access a device performing methods according to theembodiments of the disclosure.

In the embodiments of the disclosure, a component included in thedisclosure is expressed in a singular or plural form depending on thedescribed embodiments of the disclosure. However, singular or pluralexpressions are selected to be suitable for the presented situations forconvenience, and the disclosure is not limited to the singular or pluralform. An element expressed in a plural form may be configured as asingle element, or an element expressed in a singular form may beconfigured as a plurality of elements.

According to embodiments of the disclosure, a method and apparatus foreffectively providing a service in a mobile communication system areprovided. Furthermore, according to embodiments of the disclosure, amethod and apparatus for transmitting and receiving signals by usingmultiple beams are provided.

The embodiments of the disclosure disclosed in the present specificationand the accompanying drawings have been provided only as specificexamples in order to assist in understanding the disclosure and do notlimit the scope of the disclosure. It is obvious to those of ordinaryskill in the art that other modifications may be made based on thetechnical spirit of the disclosure without departing from the scope ofthe disclosure. The embodiments of the disclosure may be combined witheach other for operation when necessary. For example, an embodiment ofthe disclosure may be combined with parts of other embodiments of thedisclosure to operate a BS and a UE. Embodiments of the disclosure maybe applicable to other communication systems, and other modificationsbased on the technical spirit of the embodiments of the disclosure maybe implementable.

Although the present disclosure has been described with variousembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method performed by a user equipment (UE) in awireless communication system, the method comprising: receiving, from abase station (BS), physical downlink shared channel (PDSCH)configuration information including a list of transmission configurationindicator (TCI) states; receiving, from the BS, a PDSCH media accesscontrol element (MAC CE) including information indicating an activationof at least one TCI state in the list of TCI states, the PDSCH MAC CEbeing associated with a logical channel identifier (LCD) value;identifying that the PDSCH MAC CE is a MAC CE capable of indicating twoor more TCI states for one TCI codepoint based on the LCD valueassociated with the PDSCH MAC CE; receiving, from the BS, downlinkcontrol information (DCI) including information indicating a TCIcodepoint; and receiving, from the BS, data via a PDSCH based on theinformation indicating the activation of the at least one TCI state andthe information indicating the TCI codepoint, wherein the informationindicating the activation of the at least one TCI state comprises anidentifier of a first TCI state mapped to a first TCI codepoint and anindicator indicating whether an identifier of a second TCI state mappedto the first TCI codepoint is present, wherein the identifier of thesecond TCI state is included in the information indicating theactivation of the at least one TCI state in case that a value of theindicator is 1, wherein the identifier of the second TCI state is notincluded in the information indicating the activation of the at leastone TCI state in case that a value of the indicator is 0, and wherein bythe information indicating the activation of the at least one TCI state,for at least one TCI codepoint, two TCI states are indicated.
 2. Themethod of claim 1, wherein the receiving, from the BS, of the data viathe PDSCH comprises receiving a first PDSCH transmission to which thefirst TCI state is applied and a second PDSCH transmission to which thesecond TCI state is applied, and wherein the first PDSCH transmissionand the second PDSCH transmission are associated with a same transportblock (TB).
 3. The method of claim 1, wherein: the informationindicating the activation of the at least one TCI state comprises TCIstate identifiers for up to eight TCI codepoints, and one or two TCIstates are mapped to each of the TCI codepoints.
 4. A method performedby a base station (BS) in a wireless communication system, the methodcomprising: transmitting, to a user equipment (UE), physical downlinkshared channel (PDSCH) configuration information including a list oftransmission configuration indicator (TCI) states; transmitting, to theUE, a PDSCH media access control element (MAC CE) including informationindicating an activation of at least one TCI state in the list of TCIstates, the PDSCH MAC CE being capable of indicating two or more TCIstates for one TCI codepoint, the PDSCH MAC CE being associated with alogical channel identifier (LCD) value; transmitting, to the UE,downlink control information (DCI) including information indicating aTCI codepoint; and transmitting, to the UE, data via a PDSCH based onthe information indicating the activation of the at least one TCI stateand the information indicating the TCI codepoint, wherein theinformation indicating the activation of the at least one TCI statecomprises an identifier of a first TCI state mapped to a first TCIcodepoint and an indicator indicating whether an identifier of a secondTCI state mapped to the first TCI codepoint is present, wherein theidentifier of the second TCI state is included in the informationindicating the activation of the at least one TCI state in case that avalue of the indicator is 1, wherein the identifier of the second TCIstate is not included in the information indicating the activation ofthe at least one TCI state in case that a value of the indicator is 0,and wherein by the information indicating the activation of the at leastone TCI state, for at least one TCI codepoint, two TCI states areindicated.
 5. The method of claim 4, wherein transmitting, to the UE,the data via the PDSCH comprises transmitting a first PDSCH transmissionto which the first TCI state is applied and a second PDSCH transmissionto which the second TCI state is applied, and wherein the first PDSCHtransmission and the second PDSCH transmission are associated with asame transport block (TB).
 6. The method of claim 4, wherein: theinformation indicating the activation of the at least one TCI statecomprises TCI state identifiers for up to eight TCI codepoints, and oneor two TCI states are mapped to each of the TCI codepoints.
 7. A userequipment (UE) in a wireless communication system, the UE comprising: atransceiver; and a processor operably connected to the transceiver, theprocessor configured to: receive, from a base station (BS), physicaldownlink shared channel (PDSCH) configuration information including alist of transmission configuration indicator (TCI) states, receive, fromthe BS, a PDSCH media access control element (MAC CE) includinginformation indicating an activation of at least one TCI state in thelist of TCI states, the PDSCH MAC CE being associated with a logicalchannel identifier (LCD) value, identify that the PDSCH MAC CE is a MACCE capable of indicating two or more TCI states for one TCI codepointbased on the LCID value associated with the PDSCH MAC CE, receive, fromthe BS, downlink control information (DCI) including informationindicating a TCI codepoint, and receive, from the BS, data via a PDSCHbased on the information indicating the activation of the at least oneTCI state and the information indicating the TCI codepoint, wherein theinformation indicating the activation of the at least one TCI statecomprises an identifier of a first TCI state mapped to a first TCIcodepoint and an indicator indicating whether an identifier of a secondTCI state mapped to the first TCI codepoint is present, wherein theidentifier of the second TCI state is included in the informationindicating the activation of the at least one TCI state in case that avalue of the indicator is 1, wherein the identifier of the second TCIstate is not included in the information indicating the activation ofthe at least one TCI state in case that a value of the indicator is 0,and wherein by the information indicating the activation of the at leastone TCI state, for at least one TCI codepoint, two TCI states areindicated.
 8. The UE of claim 7, wherein the processor is furtherconfigured to receive, from the BS, a first PDSCH transmission to whichthe first TCI state is applied and a second PDSCH transmission to whichthe second TCI state is applied, and wherein the first PDSCHtransmission and the second PDSCH transmission are associated with asame transport block (TB).
 9. The UE of claim 7, wherein: theinformation indicating the activation of the at least one TCI statecomprises TCI state identifiers for up to eight TCI codepoints, and oneor two TCI states are mapped to each of the TCI codepoints.
 10. A basestation (BS) in a wireless communication system, the BS comprising: atransceiver; and a processor operably connected to the transceiver, theprocessor configured to: transmit, to a user equipment (UE), physicaldownlink shared channel (PDSCH) configuration information including alist of transmission configuration indicator (TCI) states, transmit, tothe UE, a PDSCH media access control element (MAC CE) includinginformation indicating an activation of at least one TCI state in thelist of TCI states, the PDSCH MAC CE being capable of indicating two ormore TCI states for one TCI codepoint, the PDSCH MAC CE being associatedwith a logical channel identifier (LCD) value, transmit, to the UE,downlink control information (DCI) including information indicating aTCI codepoint, and transmit, to the UE, data via a PDSCH based on theinformation indicating the activation of the at least one TCI state andthe information indicating the TCI codepoint, wherein the informationindicating the activation of the at least one TCI state comprises anidentifier of a first TCI state mapped to a first TCI codepoint and anindicator indicating whether an identifier of a second TCI state mappedto the first TCI codepoint is present, wherein the identifier of thesecond TCI state is included in the information indicating theactivation of the at least one TCI state in case that a value of theindicator is 1, wherein the identifier of the second TCI state is notincluded in the information indicating the activation of the at leastone TCI state in case that a value of the indicator is 0, and wherein bythe information indicating the activation of the at least one TCI state,for at least one TCI codepoint, two TCI states are indicated.
 11. The BSof claim 10, wherein the processor is further configured to transmit afirst PDSCH transmission to which the first TCI state is applied and asecond PDSCH transmission to which the second TCI state is applied,wherein the first PDSCH transmission and the second PDSCH transmissionare associated with a same transport block (TB).
 12. The BS of claim 10,wherein: the information indicating the activation of the at least oneTCI state comprises TCI state identifiers for up to eight TCIcodepoints, and one or two TCI states are mapped to each of the TCIcodepoints.